114 lines
2.6 KiB
Go
114 lines
2.6 KiB
Go
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package statsd
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import (
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"fmt"
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"net"
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"time"
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)
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// asyncUdsWriter is an internal class wrapping around management of UDS connection
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type asyncUdsWriter struct {
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// Address to send metrics to, needed to allow reconnection on error
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addr net.Addr
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// Established connection object, or nil if not connected yet
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conn net.Conn
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// write timeout
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writeTimeout time.Duration
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// datagramQueue is the queue of datagrams ready to be sent
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datagramQueue chan []byte
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stopChan chan struct{}
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}
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// New returns a pointer to a new asyncUdsWriter given a socket file path as addr.
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func newAsyncUdsWriter(addr string) (*asyncUdsWriter, error) {
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udsAddr, err := net.ResolveUnixAddr("unixgram", addr)
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if err != nil {
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return nil, err
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}
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writer := &asyncUdsWriter{
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addr: udsAddr,
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conn: nil,
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writeTimeout: defaultUDSTimeout,
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// 8192 * 8KB = 65.5MB
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datagramQueue: make(chan []byte, 8192),
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stopChan: make(chan struct{}, 1),
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}
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go writer.sendLoop()
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return writer, nil
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}
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func (w *asyncUdsWriter) sendLoop() {
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for {
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select {
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case datagram := <-w.datagramQueue:
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w.write(datagram)
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case <-w.stopChan:
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return
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}
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}
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}
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// SetWriteTimeout allows the user to set a custom write timeout
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func (w *asyncUdsWriter) SetWriteTimeout(d time.Duration) error {
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w.writeTimeout = d
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return nil
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}
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// Write data to the UDS connection with write timeout and minimal error handling:
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// create the connection if nil, and destroy it if the statsd server has disconnected
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func (w *asyncUdsWriter) Write(data []byte) (int, error) {
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select {
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case w.datagramQueue <- data:
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return len(data), nil
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default:
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return 0, fmt.Errorf("uds datagram queue is full (the agent might not be able to keep up)")
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}
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}
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// write writes the given data to the UDS.
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// This function is **not** thread safe.
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func (w *asyncUdsWriter) write(data []byte) (int, error) {
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conn, err := w.ensureConnection()
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if err != nil {
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return 0, err
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}
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conn.SetWriteDeadline(time.Now().Add(w.writeTimeout))
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n, err := conn.Write(data)
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if e, isNetworkErr := err.(net.Error); !isNetworkErr || !e.Temporary() {
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// err is not temporary, Statsd server disconnected, retry connecting at next packet
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w.unsetConnection()
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return 0, e
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}
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return n, err
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}
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func (w *asyncUdsWriter) Close() error {
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close(w.stopChan)
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if w.conn != nil {
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return w.conn.Close()
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}
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return nil
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}
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func (w *asyncUdsWriter) ensureConnection() (net.Conn, error) {
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if w.conn != nil {
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return w.conn, nil
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}
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newConn, err := net.Dial(w.addr.Network(), w.addr.String())
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if err != nil {
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return nil, err
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}
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w.conn = newConn
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return newConn, nil
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}
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func (w *asyncUdsWriter) unsetConnection() {
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w.conn = nil
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}
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